> 1.many people make an extra id field and choose this id field to be the
> p-key,
> but then the same person can be present twice in the table (with different
> id fields), the id in itself has no real meaning
> 2.or u can choose the "natural" key for each person, lets say a name and
the
> birthda
U have for example something like this
create table persons(
(id..),
surename ..,
familyname ..,
street ..,
..,
birthdate,..
)
a table containing the data of persons, each persons should of course be
present only once;
and one should still define a primary key,
there are two options now,
1.many p
